1. Field of the Invention
The invention relates to catheters used to drain cerebrospinal fluid from the ventricles of a brain and more particularly relates to a device for preventing the closure of such a catheter having a slit tip at the end of the shunt.
2. Description of Related Art
A typical adult has a total of about 120-150 cc of (cerebrospinal fluid) CSF with about 40 cc in the ventricles in the brain. A typical adult also produces about 500 cc/day of CSF, all of which is reabsorbed into the blood stream on a continuous basis. CSF is comprised primarily of water but also includes small amounts of minerals and proteins.
Hydrocephalus is a condition of excessive accumulation of CSF in the ventricles or brain cavities. Hydrocephalus can result from congenital conditions interfering with normal CSF circulation or as the result of a problem with CSF reabsorbtion.
Excessive accumulation of CSF, due to hydrocephalus causes increased pressure upon the brain. Whatever the cause, over time, this increased CSF pressure causes damage to the brain tissue. It has been found that shunting the excess CSF to another area of the body pressure is therapeutically beneficial and generally allows the patient to lead a full and active life.
To treat the condition of hydrocephalus a shunt is used as a conduit to transport CSF from one location in the body to another. A typical shunt for transporting CSF from the ventricle to another part of the body is comprised of a ventricular catheter, valve and distal catheter. CSF shunts also exist for transporting fluid from the spine to another part of the body.
A common material for shunt catheters is silicone. Examples of systems to continuously drain excess CSF from the ventricles of the brain are the Delta(copyright) Shunt and the CSFxe2x80x94Flow Control Shunt Assembly made and sold by Medtronicxe2x80x94PS Medical of Goleta, Calif. Such systems use a catheter 2 that is placed in the patient""s ventricle 4 in the brain 6 (FIG. 14) to drain the excess CSF.
All of these systems continuously transport excess accumulation of CSF from the patient""s ventricle through the catheter 2 to another part of the family. It has been shown to be highly advantageous to use fiber-optic technology to help place a ventricular catheter such as catheter 2 in the ventricles 4 of a brain 6. To this end, as shown in FIG. 5, endoscopes 8 have been developed that are passed through the central lumen 16 of the catheter 2. These endoscopes 8 are advanced beyond the ultimate ventricular end 10 of the catheter 2 once the catheter 2 has been placed in the ventricle 4 of the brain 6.
As the endoscope 8 is advanced beyond the ultimate ventricular end 10 of the catheter 2, the physician is able to view the environment of the ventricle 4 to determine whether the catheter 2 is placed at a desirable location. If the catheter 2 is not located at a desirable location, the physician can change the location of the catheter 2 and confirm, by viewing the location through the endoscope 8, that the final location of the ultimate ventricular end 10 of catheter 2 is a desired location.
In such a system incorporating both an endoscope 8 and a catheter 2, catheter 2 is preferably of the type disclosed in U.S. Pat. No. 5,738,666 issued to David A. Watson and Lori Cone Speckman on Apr. 14, 1998 entitled xe2x80x9cSlit Tip Ventricular Catheter and Method of Manufacturing Samexe2x80x9d, the teaching of which is incorporated herein in its entirety by reference. Such a catheter is shown in FIGS. 1-6 generally labeled 2. Catheter 2 has a proximal end 12, a distal end 14 and a central lumen 16. A plurality of holes 18 are located at the distal end 14. A valve is attached proximal to the plurality of holes 18.
A slit 20 is located at the ultimate ventricular end 10. Slit 20 extends across the ultimate ventricular end 10. Slit 20 is defined by a first side wall 22 and a second side wall 24 that meet at contact points 26 and 28. First and second side walls 22, 24 each have a midpoint 30. When slit 20 is closed, first side wall 22 is in contact with second side wall 24 along substantially the entire length of both first and second side walls 22, 24. When slit 20 is open, first and second side walls 22, 24 are separated at their respective midpoints 30. Such a catheter 2 is the Model #99102 xe2x80x9cInnervision Catheterxe2x80x9d sold by Medtronicxe2x80x94PS Medical of Goleta, Calif.
In use, as shown in FIG. 2, when the distal end 34 of an endoscope 8 is passed through catheter 2, the distal end 34 will contact slit 20. As shown in FIG. 3, as distal end 34 is advanced distally, distal end 34 will pass through slit 20 and extend distally beyond the ultimate ventricular end 10 of catheter 2.
Catheter 2 is typically made. of silicone. During storage, slit 20 will be in the xe2x80x9cclosedxe2x80x9d position so that first and second side walls 22, 24 will be in contact along substantially their entire lengths. A problem with this is that when silicone comes into contact with silicone for an extended time period, silicone to silicone bonds forms. This phenomenon is called xe2x80x9ccontact bondingxe2x80x9d. With catheter 2, when catheter 2 is in the xe2x80x9cclosedxe2x80x9d position, contact bonding begins to occur between first and second side walls 22, 24. This tends to xe2x80x9cclosexe2x80x9d slit 20 so that slit 20 will not easily xe2x80x9copenxe2x80x9d when needed as the distal end 34 of endoscope 8 is advanced through slit 20. This is a problem in need of a solution.
Although catheter 2 has been described as being made of silicone, the problem of the slit 20 closing due to bond formation may also occur in catheters made of any polymeric material susceptible to contact bonding. Examples of such polymeric material include, but are not limited to, natural and synthetic latex, plastized PVC, thermoplastic elastomers and polyurethanes as will be clear to those skilled in the art.
An insert is disclosed that is placed in the slit in a slit tipped catheter during storage and transport of the catheter. This insert prevents the opposite sides of the slit from contacting and forming bonds that tend to close the slit. When the catheter is to be used, the insert is removed and the catheter is used in its intended way.
It is therefore a primary object of the invention to provide a device that prevents the slit in a slit tipped catheter made of a material susceptible to contact bonding from closing due to bonds forming between opposite sides of the slit during storage and transport of the catheter.
It is another object of one embodiment of the invention to provide a device that prevents the slit in a slit tipped catheter made of a material susceptible to contact bonding from closing due to bonds forming between opposite sides of the slit during storage and transport of the catheter that will not adversely affect the ultimate operation of the catheter.
These and other objects of the invention will be clear from the description of the invention given herein and particularly with reference to the attached drawings and the Detailed Description of the Invention. Throughout this description, like reference numbers refer to like elements.